113f4bb17d
Currently "wxHTML Overview" refers to http://www.mozilla.org/ as a high-end HTML browser engine, while already available wxWebView doesn't get the attention it deserves. Closes https://github.com/wxWidgets/wxWidgets/pull/1975
589 lines
18 KiB
C
589 lines
18 KiB
C
/////////////////////////////////////////////////////////////////////////////
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// Name: html.h
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// Purpose: topic overview
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// Author: wxWidgets team
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// Licence: wxWindows licence
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/////////////////////////////////////////////////////////////////////////////
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/**
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@page overview_html wxHTML Overview
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@tableofcontents
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The wxHTML library provides classes for parsing and displaying HTML.
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It is not intended to be a high-end HTML browser. If you are looking for
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something like that use wxWebView.
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wxHTML can be used as a generic rich text viewer - for example to display
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a nice About Box (like those of GNOME apps) or to display the result of
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database searching. There is a wxFileSystem class which allows you to use
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your own virtual file systems.
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wxHtmlWindow supports tag handlers. This means that you can easily
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extend wxHtml library with new, unsupported tags. Not only that,
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you can even use your own application-specific tags!
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See @c src/html/m_*.cpp files for details.
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There is a generic wxHtmlParser class, independent of wxHtmlWindow.
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@section overview_html_quickstart wxHTML Quick Start
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@subsection overview_html_quickstart_disphtml Displaying HTML
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First of all, you must include @c wx/wxhtml.h.
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Class wxHtmlWindow (derived from ::wxScrolledWindow) is used to display HTML
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documents.
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It has two important methods: wxHtmlWindow::LoadPage and wxHtmlWindow::SetPage.
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LoadPage loads and displays HTML file while SetPage displays directly the
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passed @b string. See the example:
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@code
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mywin->LoadPage("test.htm");
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mywin->SetPage("htmlbody"
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"h1Error/h1"
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"Some error occurred :-H)"
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"/body/hmtl");
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@endcode
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@subsection overview_html_quickstart_settingup Setting up wxHtmlWindow
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Because wxHtmlWindow is derived from ::wxScrolledWindow and not from
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wxFrame, it doesn't have visible frame. But the user usually wants to see
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the title of HTML page displayed somewhere and the frame's titlebar is
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the ideal place for it.
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wxHtmlWindow provides 2 methods in order to handle this:
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wxHtmlWindow::SetRelatedFrame and wxHtmlWindow::SetRelatedStatusBar.
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See the example:
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@code
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html = new wxHtmlWindow(this);
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html->SetRelatedFrame(this, "HTML : %%s");
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html->SetRelatedStatusBar(0);
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@endcode
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The first command associates the HTML object with its parent frame
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(this points to wxFrame object there) and sets the format of the title.
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Page title "Hello, world!" will be displayed as "HTML : Hello, world!"
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in this example.
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The second command sets which frame's status bar should be used to display
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browser's messages (such as "Loading..." or "Done" or hypertext links).
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@subsection overview_html_quickstart_custom Customizing wxHtmlWindow
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You can customize wxHtmlWindow by setting font size, font face and
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borders (space between border of window and displayed HTML). Related functions:
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@li wxHtmlWindow::SetFonts
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@li wxHtmlWindow::SetBorders
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@li wxHtmlWindow::ReadCustomization
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@li wxHtmlWindow::WriteCustomization
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The last two functions are used to store user customization info wxConfig stuff
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(for example in the registry under Windows, or in a dotfile under Unix).
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@section overview_html_printing HTML Printing
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The wxHTML library provides printing facilities with several levels of
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complexity. The easiest way to print an HTML document is to use the
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wxHtmlEasyPrinting class.
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It lets you print HTML documents with only one command and you don't have to
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worry about deriving from the wxPrintout class at all. It is only a simple
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wrapper around the wxHtmlPrintout, normal wxWidgets printout class.
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And finally there is the low level class wxHtmlDCRenderer which you can use to
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render HTML into a rectangular area on any DC. It supports rendering into
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multiple rectangles with the same width. The most common use of this is placing
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one rectangle on each page or printing into two columns.
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@section overview_html_helpformats Help Files Format
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wxHTML library can be used to show an help manual to the user; in fact, it
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supports natively (through wxHtmlHelpController) a reduced version of MS HTML
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Workshop format.
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A @b book consists of three files: the header file, the contents file
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and the index file.
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You can make a regular zip archive of these files, plus the HTML and any image
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files, for wxHTML (or helpview) to read; and the @c ".zip" file can optionally
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be renamed to @c ".htb".
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@subsection overview_html_helpformats_hhp Header file (.hhp)
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The header file must contain these lines (and may contain additional lines
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which are ignored):
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@code
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Contents file=filename.hhc
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Index file=filename.hhk
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Title=title of your book
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Default topic=default page to be displayed.htm
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@endcode
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All filenames (including the Default topic) are relative to the
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location of the @c ".hhp" file.
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@note For localization, in addition the @c ".hhp" file may contain the line
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@code
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Charset=rfc_charset
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@endcode
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which specifies what charset (e.g. "iso8859_1") was used in contents
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and index files. Please note that this line is incompatible with
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MS HTML Help Workshop and it would either silently remove it or complain
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with some error. See also @ref overview_nonenglish.
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@subsection overview_html_helpformats_hhc Contents file (.hhc)
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Contents file has HTML syntax and it can be parsed by regular HTML parser.
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It contains exactly one list (@c <ul>....@c </ul> statement):
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@code
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<ul>
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<li><object type="text/sitemap">
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<param name="Name" value="@topic name@">
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<param name="ID" value=@numeric_id@>
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<param name="Local" value="@filename.htm@">
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</object>
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<li><object type="text/sitemap">
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<param name="Name" value="@topic name@">
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<param name="ID" value=@numeric_id@>
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<param name="Local" value="@filename.htm@">
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</object>
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...
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</ul>
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@endcode
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You can modify value attributes of param tags. The <em>topic name</em> is name
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of chapter/topic as is displayed in contents, <em>filename.htm</em> is the HTML
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page name (relative to the @c ".hhp" file) and <em>numeric_id</em> is optional,
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it is used only when you use wxHtmlHelpController::Display(int).
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Items in the list may be nested - one @c <li> statement may contain a
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@c <ul> sub-statement:
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@code
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<ul>
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<li><object type="text/sitemap">
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<param name="Name" value="Top node">
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<param name="Local" value="top.htm">
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</object>
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<ul>
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<li><object type="text/sitemap">
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<param name="Name" value="subnode in topnode">
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<param name="Local" value="subnode1.htm">
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</object>
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...
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</ul>
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<li><object type="text/sitemap">
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<param name="Name" value="Another Top">
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<param name="Local" value="top2.htm">
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</object>
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...
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</ul>
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@endcode
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@subsection overview_html_helpformats_hhk Index Files (.hhk)
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Index files have same format as contents files except that ID params are
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ignored and sublists are @b not allowed.
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@section overview_html_filters Input Filters
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The wxHTML library provides a mechanism for reading and displaying
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files of many different file formats.
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wxHtmlWindow::LoadPage can load not only HTML files but any known file.
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To make a file type known to wxHtmlWindow you must create a wxHtmlFilter filter and
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register it using wxHtmlWindow::AddFilter.
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@section overview_html_cells Cells and Containers
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This article describes mechanism used by wxHtmlWinParser and
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wxHtmlWindow to parse and display HTML documents.
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@subsection overview_html_cells_cells Cells
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You can divide any text (or HTML) into small fragments. Let's call these
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fragments @b cells. Cell is for example one word, horizontal line, image
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or any other part of document. Each cell has width and height (except special
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"magic" cells with zero dimensions - e.g. colour changers or font changers).
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See wxHtmlCell.
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@subsection overview_html_cells_containers Containers
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Container is kind of cell that may contain sub-cells. Its size depends
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on number and sizes of its sub-cells (and also depends on width of window).
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See wxHtmlContainerCell, wxHtmlCell::Layout. This image shows the cells and
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containers:
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@image html overview_html_contbox.png
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@subsection overview_html_cells_conttaghandler Using Containers in Tag Handler
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wxHtmlWinParser provides a user-friendly way of managing containers.
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It is based on the idea of opening and closing containers.
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Use wxHtmlWinParser::OpenContainer to open new a container @e within an already
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opened container.
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This new container is a @e sub-container of the old one. (If you want to create a
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new container with the same depth level you can call @c CloseContainer(); OpenContainer();.)
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Use wxHtmlWinParser::CloseContainer to close the container.
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This doesn't create a new container with same depth level but it returns "control"
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to the parent container. See explanation:
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@image html overview_html_cont.png
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There clearly must be same number of calls to OpenContainer as to
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CloseContainer.
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This code creates a new paragraph (container at same depth level) with
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"Hello, world!":
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@code
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m_WParser->CloseContainer();
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c = m_WParser->OpenContainer();
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m_WParser->AddText("Hello, ");
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m_WParser->AddText("world!");
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m_WParser->CloseContainer();
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m_WParser->OpenContainer();
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@endcode
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and here is image of the situation:
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@image html overview_html_hello.png
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You can see that there was an opened container before the code was executed.
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We closed it, created our own container, then closed our container and opened
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new container.
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The result was that we had @e same depth level after executing. This is general
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rule that should be followed by tag handlers: leave depth level of containers
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unmodified (in other words, number of OpenContainer and CloseContainer calls
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should be same within wxHtmlTagHandler::HandleTag's body).
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Notice that it would be usually better to use wxHtmlContainerCell::InsertCell
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instead of adding text to the parser directly.
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@section overview_html_handlers Tag Handlers
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The wxHTML library provides architecture of pluggable @e tag handlers.
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Tag handler is class that understands particular HTML tag (or tags) and is
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able to interpret it.
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wxHtmlWinParser has a static table of @b modules.
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Each module contains one or more tag handlers. Each time a new wxHtmlWinParser
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object is constructed all modules are scanned and handlers are added
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to wxHtmlParser's list of available handlers (note: wxHtmlParser's list
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is non-static).
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@subsection overview_html_handlers_howworks How it works
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Common tag handler's wxHtmlTagHandler::HandleTag method works in four steps:
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@li Save state of parent parser into local variables
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@li Change parser state according to tag's params
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@li Parse text between the tag and paired ending tag (if present)
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@li Restore original parser state
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See wxHtmlWinParser for methods for modifying parser's state.
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In general you can do things like opening/closing containers, changing colors, fonts etc.
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@subsection overview_html_handlers_custom Providing own tag handlers
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You should create a new .cpp file and place the following lines into it:
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@code
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#include <mod_templ.h>
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#include <forcelink.h>
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FORCE_LINK_ME(yourmodulefilenamewithoutcpp)
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@endcode
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Then you must define handlers and one module.
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@subsection overview_html_handlers_tag Tag handlers
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The handler is derived from wxHtmlWinTagHandler (or directly from wxHtmlTagHandler).
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You can use set of macros to define the handler (see src/html/m_*.cpp files
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for details). Handler definition must start with @b TAG_HANDLER_BEGIN macro
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and end with @b TAG_HANDLER_END macro.
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I strongly recommend to have a look at @e include/wxhtml/mod_templ.h file.
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Otherwise you won't understand the structure of macros.
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See macros reference:
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@li @b TAG_HANDLER_BEGIN(@e name, @e tags):
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Starts handler definition. @e name is handler identifier (in fact
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part of class name), @e tags is string containing list of tags
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supported by this handler (in uppercase). This macro derives new class from
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wxHtmlWinTagHandler and implements it is wxHtmlTagHandler::GetSupportedTags method.
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Example: TAG_HANDLER_BEGIN(FONTS, "B,I,U,T")
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@li @b TAG_HANDLER_VARS:
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This macro starts block of variables definitions. (Variables are identical
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to class attributes.) Example:
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@code
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TAG_HANDLER_BEGIN(VARS_ONLY, "CRAZYTAG")
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TAG_HANDLER_VARS
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int my_int_var;
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wxString something_else;
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TAG_HANDLER_END(VARS_ONLY)
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@endcode
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This macro is used only in rare cases.
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@li @b TAG_HANDLER_CONSTR(@e name):
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This macro supplies object constructor. @e name is same name as the one
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from TAG_HANDLER_BEGIN macro. Body of constructor follow after
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this macro (you must use { and } ). Example:
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@code
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TAG_HANDLER_BEGIN(VARS2, "CRAZYTAG")
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TAG_HANDLER_VARS
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int my_int_var;
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TAG_HANDLER_CONSTR(vars2)
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{ // !!!!!!
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my_int_var = 666;
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} // !!!!!!
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TAG_HANDLER_END(VARS2)
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@endcode
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Never used in wxHTML :-)
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@li @b TAG_HANDLER_PROC(@e varib):
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This is very important macro. It defines wxHtmlTagHandler::HandleTag
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method. @e varib is name of parameter passed to the method, usually
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@e tag. Body of method follows after this macro.
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Note than you must use { and } !
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Example:
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@code
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TAG_HANDLER_BEGIN(TITLE, "TITLE")
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TAG_HANDLER_PROC(tag)
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{
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printf("TITLE found...\n");
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}
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TAG_HANDLER_END(TITLE)
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@endcode
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@li @b TAG_HANDLER_END(@e name):
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Ends definition of tag handler @e name.
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@subsection overview_html_handlers_modules Tags Modules
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You can use set of 3 macros TAGS_MODULE_BEGIN, TAGS_MODULE_ADD and
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TAGS_MODULE_END to inherit new module from
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wxHtmlTagsModule and to create instance of it.
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See macros reference:
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@li @b TAGS_MODULE_BEGIN(@e modname):
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Begins module definition. @e modname is part of class name and must be unique.
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@li @b TAGS_MODULE_ADD(@e name):
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Adds the handler to this module. @e name is the identifier from TAG_HANDLER_BEGIN.
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@li @b TAGS_MODULE_END(@e modname):
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Ends the definition of module.
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Example:
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@code
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TAGS_MODULE_BEGIN(Examples)
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TAGS_MODULE_ADD(VARS_ONLY)
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TAGS_MODULE_ADD(VARS2)
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TAGS_MODULE_ADD(TITLE)
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TAGS_MODULE_END(Examples)
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@endcode
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@section overview_html_supptags Supported HTML Tags
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wxHTML is not full implementation of HTML standard. Instead, it supports most
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common tags so that it is possible to display @e simple HTML documents with it.
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(For example it works fine with pages created in Netscape Composer or generated
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by tex2rtf).
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Following tables list all tags known to wxHTML, together with supported
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parameters.
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A tag has general form of @c tagname param_1 param_2 ... param_n where param_i
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is either @c paramname="paramvalue" or @c paramname=paramvalue - these two are
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equivalent. Unless stated otherwise, wxHTML is case-insensitive.
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@subsection overview_html_supptags_commonvalues Common Parameter Values
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We will use these substitutions in tags descriptions:
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@code
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[alignment] CENTER
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LEFT
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RIGHT
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JUSTIFY
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[v_alignment] TOP
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BOTTOM
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CENTER
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[color] HTML 4.0-compliant colour specification
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[fontsize] -2
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-1
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+0
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+1
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+2
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+3
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+4
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1
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2
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3
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4
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5
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6
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7
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[pixels] integer value that represents dimension in pixels
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[percent] i%
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where i is integer
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[url] an URL
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[string] text string
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[coords] c(1),c(2),c(3),...,c(n)
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where c(i) is integer
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@endcode
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@subsection overview_html_supptags_list List of Supported Tags
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@code
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A NAME=[string]
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HREF=[url]
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TARGET=[target window spec]
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ADDRESS
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AREA SHAPE=POLY
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SHAPE=CIRCLE
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SHAPE=RECT
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COORDS=[coords]
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HREF=[url]
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B
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BIG
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BLOCKQUOTE
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BODY TEXT=[color]
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LINK=[color]
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BGCOLOR=[color]
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BR ALIGN=[alignment]
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CENTER
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CITE
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CODE
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DD
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DIV ALIGN=[alignment]
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DL
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DT
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EM
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FONT COLOR=[color]
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BGCOLOR=[color]
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SIZE=[fontsize]
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FACE=[comma-separated list of facenames]
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HR ALIGN=[alignment]
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SIZE=[pixels]
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WIDTH=[percent|pixels]
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NOSHADE
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H1
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H2
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H3
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H4
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H5
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H6
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I
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IMG SRC=[url]
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WIDTH=[percent|pixels]
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HEIGHT=[pixels]
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ALIGN=TEXTTOP
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ALIGN=CENTER
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ALIGN=ABSCENTER
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ALIGN=BOTTOM
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USEMAP=[url]
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KBD
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LI
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MAP NAME=[string]
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META HTTP-EQUIV="Content-Type"
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CONTENT=[string]
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OL
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P ALIGN=[alignment]
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PRE
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SAMP
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SMALL
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SPAN
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STRIKE
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STRONG
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SUB
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SUP
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TABLE ALIGN=[alignment]
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WIDTH=[percent|pixels]
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BORDER=[pixels]
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VALIGN=[v_alignment]
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BGCOLOR=[color]
|
|
CELLSPACING=[pixels]
|
|
CELLPADDING=[pixels]
|
|
TD ALIGN=[alignment]
|
|
VALIGN=[v_alignment]
|
|
BGCOLOR=[color]
|
|
WIDTH=[percent|pixels]
|
|
COLSPAN=[pixels]
|
|
ROWSPAN=[pixels]
|
|
NOWRAP
|
|
TH ALIGN=[alignment]
|
|
VALIGN=[v_alignment]
|
|
BGCOLOR=[color]
|
|
WIDTH=[percent|pixels]
|
|
COLSPAN=[pixels]
|
|
ROWSPAN=[pixels]
|
|
TITLE
|
|
TR ALIGN=[alignment]
|
|
VALIGN=[v_alignment]
|
|
BGCOLOR=[color]
|
|
TT
|
|
U
|
|
UL
|
|
@endcode
|
|
|
|
@subsection overview_html_suppstyles_list Supported Styles
|
|
|
|
wxHTML doesn't really have CSS support but it does support a few simple styles:
|
|
you can use @c "text-align", @c "width", @c "vertical-align" and @c
|
|
"background" with all elements and for @c SPAN elements a few other styles are
|
|
additionally recognized:
|
|
|
|
- @c color
|
|
- @c font-family
|
|
- @c font-size (only in point units)
|
|
- @c font-style (only "oblique", "italic" and "normal" values are supported)
|
|
- @c font-weight (only "bold" and "normal" values are supported)
|
|
- @c text-decoration (only "underline" value is supported)
|
|
|
|
*/
|